This invention relates to the field of lasers.
Many applications require the generation of extremely short, high-peak-power pulses of light from a laser. Extremely short pulses refer to pulse durations of less than 100 ps. High-peak-powers will refer to peak powers of greater than 100 kW. One method for producing extremely short pulses is to mode-lock the laser. In mode-locking, several longitudinal modes of a laser are locked together such that a periodic train of extremely short pulses is produced. The period between pulses is the round-trip time of the laser cavity, typically 10 ns. Because of the large number of pulses produced each second, even lasers with high average power (10-100 W or greater) can not produce pulses with high peak powers.
High-peak-power pulses can be produced by Q switching a laser. In Q switching, the Q or "quality" of the laser cavity is changed in order to generate a pulse. The size of conventional Q-switched lasers, along with the physics of the device, precludes the production of extremely short pulses.
Extremely short, high-peak-power pulses can be obtained from either Q-switched mode-locked lasers or amplified mode-locked lasers. Both of these approaches require large (typically several feet long), complicated (requiring daily supervision by a qualified laser technician), power-hungry (several kilowatts of electrical power), and therefore, expensive devices.